1. Field of the Invention
The present invention relates to a method and an apparatus for extracting a human figure region in an image. The present invention also relates to a program that causes a computer to execute the method.
2. Description of the Related Art
For image editing such as image classification, automatic trimming, and electronic photo album generation, extraction of human figure regions and recognition of poses in images are expected. As a method of extraction of human figure regions by separation from backgrounds in images, a method described in Japanese Unexamined Patent Publication No. 2005-339363 has been known, for example. In this method, a person is photographed with a predetermined specific background, and a human figure region is cut out from the background based on the difference in colors therebetween.
In addition to the method using a predetermined background setting as has been described above, a method of separating a human figure region from any arbitrary background in an image by advance manual input of information on a portion of the human figure region and the background has been proposed in Y. Boykov and M. Jolly, “Interactive Graph Cuts for Optimal Boundary & Region Segmentation of Objects in N-D Images”, Proc. of Int. Conf. on Computer Vision, Vol. I, pp. 105-112, 2001. This method, which adopts advance specification of a portion of human figure region and background, has been used mainly for interactive cutting.
Furthermore, an automatic human figure region extraction method has been proposed in G. Mori et al., “Recovering Human Body Configurations: Combining Segmentation and Recognition”, CVPR, pp. 1-8, 2004. In this method, a whole image is subjected to region segmentation processing and judgment is made on each region as to whether the region is a portion of a human figure region based on characteristics such as the shape, the color, and texture thereof. An assembly of the regions having been judged to be the portions is automatically extracted as a human figure region.
However, in this method of human figure region extraction using the characteristics of respective regions generated through segmentation, human figure regions cannot be extracted correctly in the case where a degree of segmentation is not appropriate for human figure extraction such as cases where regions generated through segmentation are too small for accurate judgment of portions of human figure regions, or too large and include background regions as well. Therefore, the accuracy of human figure region extraction is strongly affected by the degree of segmentation in this method.